A new U.S. Congress was sworn into office Thursday, but it will quickly face an old dispute about the country's burgeoning debt and in the coming weeks controversial new gun control and immigration proposals.

The Congress leaving office squabbled this week in its final days over contentious tax and spending legislation before finally agreeing to increase taxes on the wealthiest American families. The new Congress, the country's 113th, faces a renewed debate over increasing the country's $16.4 trillion borrowing cap, a debt ceiling the government reached earlier this week.

Democratic leader Nancy Pelosi (L) introduces Speaker of the House John Boehner to speak after Boehner's re-election during the first day of the 113th US Congress in the Capitol in Washington, January 3, 2013.

As part of the opening day of ceremonies, the majority Republicans in the House of Representatives again chose Ohio congressman John Boehner as Speaker, the top position in the chamber. By U.S. law, he also is second in the line of succession for the presidency, behind Vice President Joe Biden, a Democrat.

In a time-honored ceremony, Biden swore in new and re-elected senators, asking them whether they swore allegiance to the U.S. Constitution:

"Do you solemnly swear that you will support and defend the Constitution of the United States against all enemies foreign and domestic, that you will bear true faith and allegiance to the same, that you take this obligation freely, without any mental reservation or purpose of evasion, and that you will well and faithfully discharge the duties of the office on which you are about to enter, so help you God?"

Congressional Majority, Senate

The U.S. government said it can keep paying its bills for another two months, but by then will need to have the borrowing limit increased - or face an unprecedented circumstance, running out of money and defaulting on some of its financial obligations. President Barack Obama, a Democrat, said he will not negotiate with Congress over raising the debt ceiling, but Republican lawmakers said they plan to use the borrowing debate to try to win sharp concessions from Obama to cut government spending.

Lawmakers and the White House also will have to decide which spending cuts to impose, decisions they postponed for two months while compromising on this week's tax package.

The senior economist at one of the country's largest banks, James Glassman of JPMorgan Chase, said the debt ceiling will have to be increased, perhaps by $1 trillion or so, to give the government enough borrowing room for the coming year. He predicted the debate will be rancorous and focused on the government's need to rein in spending for government medical programs for older Americans and the impoverished so that it can eventually trim its debt.

Glassman said the debate will be messy and noisy. "Increasingly over time, we're going to have to figure how to get to the real problem. The elephant in the room really is health care, federal health care spending. That's what's expected to grow steadily over the years," he added.

113 Congress - House

Obama, set to be sworn in for a second term on January 20, said he plans to send Congress new gun control legislation later this month in the wake of last month's schoolhouse shooting rampage that left 20 children and six adults dead. In addition, he said he hopes to enact sweeping immigration reforms this year.

As a result of the November elections, Obama will have a slightly bigger Democratic Party contingent in Congress to work with. Democrats have a 55-45 edge in the Senate, a gain of two seats. Republicans continue to control the 435-member House of Representatives, but with a reduced majority. Republicans hold 234 House seats, down from 242, while the Democrats hold 201 seats.

The new Congress includes 12 new senators and 84 new House members. While the demographic makeup of the overall Congress will remain whiter, older and more male than the country as a whole, the new lawmakers are the most diverse in history, particularly the House Democratic delegation.

Among the new lawmakers are four African-Americans, 10 Latinos, five Asian-Americans and 24 women. There are also two Hindus, a Buddhist and the first openly bisexual congresswoman.